The presence of high levels of temporary hardness (high alkalinity) in the raw water supply feeding a highly rated package boiler can result in high blowdown rates and an associated very high level of carbon dioxide in the steam. The resultant condensate has an acidic pH and the water is very aggressive to the metals in the condensate system.
Iron fouling of steam traps, poor operation of steam traps and high cost of replacement condensate pipework can result in a significant on cost to the boiler operation. To treat this type of water related problem requires consideration be given to the Derwent Dealkalisation/Degas/Base Exchange plant.
The reliable Derwent standard range of Degas-Base Exchange Dealkalisation Plant effectively reduces the alkalinity and hardness salts from the water giving a water of the following composition:
- Bicarbonate alkalinity – less than 5% average of the input alkalinity
- Total dissolved solids reduction – approximately equal to the temporary hardness
- Total hardness – less than 4 ppm
Derwent Water Services has standard modules for:
- Break tanks
- Raw water and degas booster pump sets
- Dealkalisation columns
- Degasser towers
- Acid measure tanks
- pH correction and caustic sets
- Softening columns
Combining the standard modular dealkalisation range with the standard softening plant range gives a fully dealkalised and fully softened water.
For plants not wishing to have acid on site for regeneration and for sites with space restrictions which limit a degasser tower, Derwent has available a “Chloride Regenerated Anion Dealkalisation Plant”.
In certain areas, where the waters contain high levels of sodium bicarbonate, Derwent Water Systems recommends a more specialised “Split Stream Dealkalisation Plant”.